cranial nervus 2

8/10/2019 Cranial Nervus 2

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CRANIAL NERVES

Dr. Hj. Meiti frida, Sp.S

Department of NeurologyMedical Faculty Andalas University -

Dr. M. Djamil Hospital

Padang


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What are cranial nerves ?

Is the twelve pairs of nerve that has itsorigin at the base of the brain

Not all of peripheral nerves , as the

olfactory bulb and optic nerve are in factextention of the Brain

The rest are differentiated from somatic

peripheral nerve, not only by theirlocations, but also they all have different/

spesific functions


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Cranial

Nerves


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Cranial

NerveNuclei


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Motoric

CranialNerves

Nuclei


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Sensoric

Cranial

Nerves

Nuclei


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Examples:Some function as special senses, like

Olfactory Olfactory nerve (I)

Vission Optic nerve(II)

Hearing and equilibrium

Stato-acustic nerve(VIII) Taste Trigemimenal-Fascial (V,VII)

Glossopharyngeal (IX)

Pure motor function

Trochlear (IV)

Abducens(VI)

Hypoglossal (XII)


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What is the use in understanding

cranial nerve

For localizing diseases at be the base of theskull or brainstem

This include knowledge of the anatomy of :

Base of the skull

Structures (nuclei and tracts) in the

brainstem

Help us in clinical diagnosis of brain death, inthe absence of EEG or other diagnosticapparatus


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Nuclei of Cranial nerves

Some nuclei serve only one nerve, likethe motor nuclei to the Abducens(VI)

nerve The Nucleus Solitarius takes fiber from

the anterior 2/3 of the tongue, through the5thnerve (Lingual branch), through the

chorda tympani, and the 7thnerve. Butfrom taste buds of the posterior 1/3,through the glossopharyngeal nerve


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Distribution Area of Cranial

nerves

While most extent just around the head,

Vagus (X), which is a parasympathic nerve sent

itsfibers to the chest and abdominal cavity,influencing the heart and the intestines until 2/3

of the colon.

The olfactory nerve on the other hand is only a

few millimeters long, penetrating the laminacribrosa, from the top of the nasal cavity to the

olfactory bulb


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I . Olfactory nerve

Brings the sense of smell from the nasal cavity

to the Olfactory bulb to the brain.

Because of so fine it is easily ruptured during ahead injury

The second cause of illness is frontal base

tumor and olfactory grove meningioma

Injury to this nerve make people complain of

loss of appetite


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N. I


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N. I


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II. Optic nerve The optic nerve serves our vision

Injury to the nerve may cause disturbance of ;Visual acuity : Sharpness of vision or

Visual field defect It depends on the cause of illness and the

location of injury

Papil edema : blurring of the optic disk on

ophthalmoscopic examination, is mostly asign of increased intracranial pressure

but can found also in optic nerveinflammation and malignant hypertension


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N. II


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Convergenceand

Accomodation


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III.Oculomotor nerve, IV. trochlear

nerve, VI. Abducens

All this three-nerve synchronously moveboth the eye-ball so that we will have

optimal vision The 3th and 4thnerve have their nuclei in

the Mesencephalon

The 6thnerve has its nuclei in the pons

The 6thnerve move the eye-ball to theside, an the 4thto the mid and downward.


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All other movements of the eye, including

moving the Eyelid upward, are the function ofthe 3rdnerve.

The 6thnerve travels the farthest on the baseof the skull, and is prone to paralysis during

chronic increased intracranial pressure In the cavernous sinus, those three nerves

travel together

All enter the optic cavity through the superior

fissure


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N. III, IV and VI


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3rdNerve Nuclei


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N. III, IV, V & VI


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Location of injury Total ophthalmoplegia, the most likely place

is in the cavernous sinus

Injury of the brainstem (mesencephalon)

usually gives only a partial 3rd

nerve palsy,but may be accompanied by contra-lateralhemiplegia

Injury of the side of the pons, may give 6th

nerve palsy, accompanied by 7th

nerve palsy,and contra-lateral hemiplegia

Diseases behind of the eye give also mostlypartial ophthalmoplegia

N III IV d VI


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N. III, IV, and VI


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Conjugate eye movement The left and right eye move synchronously, so

images is percieved as one in the brain.

The centre of lateral conjugate movement is at

the side of the 6thNerve, from where fibers go tothe Nuclei of the Medial Rectus, through the

Medial Lemniscus.

The center of horizontal movement is at thesuperior colliculus at the back of mesencephalon.

Damage of the Medial Lemniscus causes

Internuclear ophthalmoplegia


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Conjugate

movement


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V.Trigeminal Nerve This is the main sensory nerve of the face

(Portio Mayor), and inervates the muscles ofmastication (Portio Minor)

It has three branches: Ophthalmic, Maxilary,and Mandibular

Nerve from the taste buds travels first throughthe Lingual nerve, than through the ChordaTympani of the Fascial nerve (VII), to theSolitary Nuclei in the midbrain

Reversely, fibers to the submandibular andsubLingual glands, travel from the superiorSalivatory Nuclei, throught the 7thnerve(Intermedius) and Chorda Tympani .


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N. V


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VII. Fascial nerve

This nerve predominantly innervates thefascial muscles

Taste fibers and motor fiber to the Lacrimal ,and salivatory gland travel first with the fascial

motor fibers until the fascial channel Just after entering the internal acustic meatus

it gives branches to the lacrimal gland.

The taste and salivatory fibers cross to the

5thnerve through the chorda tympani.

Before exiting through the external acousticmeatus, it give a motoric branch to thestapedius muscle of the tympanic menbrane


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N. VII


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TastePathway


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GlandInnervation


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Central and Peripheral Fascial Palsies

In peripheral fascial palsies, the whole side of

the face is paralysed

There may also be Gustatory disturbances,and Tinnitus due to paralysis of the Stapedius

muscle

Central or Supra-Nuclear palsies like in strokes,

show only paralysis of the lower-half of the face,as the part of Nuclei serving the upperhalf is

bilaterally innervated.


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Central 7th palsy Peripheral 7th palsy


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VIII. Stato-acustic nerve This is a short nerve traveling with the 7th

nerve at the cerebello-pontine angle to theInternal auditory foramen. After entering thepetrosal bone it branches to the Cochleaand semicircular channels

In traumatic petrosal fractures, it may bedamaged together with the Fascial nerve

An acoustic sheet meningioma, may causean early rise of intracranial pressure

The acoustic portion, may also be damagedby Streptomycine


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N. VIII


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Central

Pathway of

Cochlear

Nerve


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Centralpathway of

vestibular

nerve


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IX. Glossopharyngeal

This is a predominantly sensory nerve , servingthe Pharynx and Larynx,

The Ambiguus Nuclei serve the muscles of the

pharynx and larynx, but the most dominant partpass through the Vagus nerve

It takes also nerves from the the Baro andChemo-receptors in the carotid Body,

The fibers of taste buds from the posterior 1/3of the tongue and Pharynx also pass throughthis nerve to the Solitary Nuclei


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N. IX


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X. Vagus Nerve

This is the most important nerve

From the Ambiguus Nuclei it sends motorfibers to most of muscle in the pharyx andLarynx

From the Parasympathic Dorsal Nuclei, sends

parasympatic branches to the Thoracic andAbdominal cavity.

The superior laryngeal nerve serves theexternal Vocal muscles, while the inferiorLaryngeal nerve after went down first andpassing the Brachial vessel on the right andthe aortic arc on the left went back upward tothe muscles of the Vocal cord


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N. X


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IX Accessory Nerve

This is a relative minor nerve

The cephalic part joint the Vagus nerve

The cervical part is an in fact somaticnerve, arises from the cervical medulla,

which past first upward, through the

Foramen Magnum, and then downward tothe Stercocleidomastoideus and

Trapezius muscles


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N. XI


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XII Hypoglossal Nerve

This is a motoric nerve serving the muscles ofthe tongue

We have external muscles, which move the

tongue to all directions, and internal muscleswhich can thicked or flatten or curl the tongue

In stroke, paralysis of one side of the Genio-hyoid muscle, causes the tongue protrude to

the paralysed side

In chronic peripheral nerve lesions the tongueflattened and Fasciculated


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N. XII


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cranial nervus 2

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